Vacuum systems are widely used in scientific research and industry. Among many important technology fields that need high vacuum system is the semiconductor manufacturing field. Frequently the performance of devices highly depends on the pressure and impurities present in a vacuum system. Residual gases and/or other impurities in the growth environment could be a significant source of contamination of the product.
Ultra high vacuum regime is the vacuum regime characterized by pressure lower than 10−9 Torr, and is not trivial to achieve. Though pumps can continue to remove particles from a vacuum chamber in an attempt to decrease the pressure in the vacuum chamber, gases enter the vacuum chamber by surface desorption from the chamber's walls or permeation through the walls. Especially when pressure is low, the pressure difference between the inside of the chamber and the ambient environment outside the vacuum chamber makes permeation more serious.
Cryogenic pumps are one type of vacuum device that can be used to attempt to achieve ultra-high vacuum conditions by removing gases from a sealed vacuum chamber at low temperature. Cryogenic pumps trap particles by condensing them on a cold surface.